Current methods for the treatment of ectoparasites, e.g. lice, typically utilize insecticidal compositions which are available in both prescription and over-the-counter formulations. Such compositions generally include one or more of the active ingredients benzyl benzoate, pyrethrin, permithrin, and lindane. Dispensing formulations include lotions, creams, shampoos, cream rinses, and gels.
However, increasing numbers of ectoparasite infections, especially head lice, that are resistant to the above insecticides have been reported in the medical literature.
Alternative insecticidal treatments such as the use of malathion, ivermectin, and a combination of trimethoprim and sulfamethazole have been tried, but usually only with mixed results.
Another approach that has been reported and which is at least partially effective is the use of a topical petrolatum-containing product, which suffocate the parasites when left on the head for a prolonged period of time. However, removal of the petrolatum from the head and hair has proven to be a difficult problem, often taking about ten days for complete removal.
Oil based occlusive treatments have been observed to significantly immobilize and coat the lice long enough for asphyxiation to occur. However, some adult lice survived even after an overnight treatment. Meinking, T L, Burkhart C G, Burkhart C N, Ectoparasitic Disease in Dermatology: Reassessment of Scabies and Pediculosis, Advances in Dermatology, Chapter 3, pp 99, Mosby Inc. 1999.
Head lice have been on the increase in the recent past, in large part due to the fact that they have become more tolerant or resistant to conventional treatments. For this reason children are being over-treated with pesticide-containing products as well as other unconventional treatments in an effort to control this epidemic. Many parents and health professionals have turned to unproven and generally ineffective alternative products such as mayonnaise, olive oil, etc. Unfortunately, others have turned to very dangerous alternatives such as gasoline, kerosene or traumatizing measures such as head shaving.
It was recently discovered by the present inventor that ectoparasites on animal skin can be treated successfully by a method comprising the steps of:                I) applying to the skin affected by ectoparasites a water-soluble or water-dispersible, substantially air-impermeable liquid barrier composition;        II) leaving the composition in contact with the skin until the ectoparasites have been killed by suffocation; and        III) removing the composition and the dead ectoparasites from the skin.        
See U.S. Pat. Nos. 5,858,383 and 6,139,859.